add tests for converters, utils, signals

aircox/models/signals.py

@@ -53,8 +53,10 @@ def page_post_save(sender, instance, created, *args, **kwargs):
 def program_post_save(sender, instance, created, *args, **kwargs):
     """Clean-up later diffusions when a program becomes inactive."""
     if not instance.active:
-        Diffusion.object.program(instance).after(tz.now()).delete()
-        Episode.object.parent(instance).filter(diffusion__isnull=True).delete()
+        Diffusion.objects.program(instance).after(tz.now()).delete()
+        Episode.objects.parent(instance).filter(
+            diffusion__isnull=True
+        ).delete()
 
     cover = getattr(instance, "__initial_cover", None)
     if cover is None and instance.cover is not None: